Abrading machine with a plurality of abrasive wheels



P 1968 E. SCHMIDT 3,376,72

ABRADING MACHINE WITH A PLURALITY OF ABRASIVE WHEELS Filed Feb. 9, 19654 Sheets-Sheet 1 g E L 6 INVENTOR. Erich Schmidf Attorney April Q, 1958E. SCHMIDT 3 9 ABRADING MACHINE WITH A PLURALITY 0F ABRASIVE WHEELSINVENTOR. Erich Schmiclf N A Attorney April 9, 1968 DT 3,376,672

ABRADING MACHINE WITH A PLURALITY OF ABRASIVE WHEELS Filed Feb. 9, 19654 Sheets-Shee1 3 g g E 36 l INVENTOR; Erich Schmidf Apr-i3 9, 1968 E.SCHMIDT 3,376,672

ABRADING MACHINE WITH A PLURALITY OF ABRASIVE WHEELS Filed Feb. 9, 19654 Sheets-Sheet Q Erich Schmid? BY f Attorney" 3,376,672 Patented Apr. 9,1968 3,376,672 ABRADING MACHINE WITH A PLURALITY 0F ABRASIVE ELS ErichSchmidt, Vienna, Austria, assignor to Fa. Maschinenfabrik ZuckermannKom. Ges. Wien, Vienna,

Austria Filed Feb. 9, 1965, Ser. No. 431,331 Claims priority,application Austria, Feb. 14, 1964, A 1,266/64 14 (Ilaims. (Cl. 51-76)ABSTRACT OF THE DISCLOSURE Machine for the abrading of a succession ofelongated workpieces displaced along a linear transport path by aconveyor belt in which pairs of abrasive wheels are spaced along thispath at different angular orientations to surface predetermined linearstretches of each workpiece, the wheels of each pair being rotated inopposite senses by flexible shafts and respective motors while a camarrangement includes cams individual to each wheel, respectivecam-follower levels and Bowden lines displace the wheels in accordancewith a predetermined pattern so that one wheel of each pair engages oneend of the respective workpiece but is lifted before it sweeps thesecond end, and the second wheel engages the second end without contactwith the first end to maintain the sharpness of the edges at the endfaces of the workpieces.

The invention relates to a grinding machine having a plurality ofabrasive wheels successively abrading a workpiece.

According to the present invention, there is provided a machine forgrinding the surface of an elongate workpiece having sharp edgesdisposed transversely of its longitudinal direction, said machinecomprising first and second abrasive wheels, means for effectingrelative linear movement between the wheels and workpiece along thelength thereof, means for rotating the wheels in a common planecontaining the line of said linear movement and in opposite senseswhereby the movements of the operative surfaces of said first and secondgrinding wheels are respectively with and against the movement of saidworkpiece relative to said wheels, and actuating means for ensuring thatthe first wheel contacts the leading transverse edge of the workpiecebut does not contact the trailing edge thereof and for ensuring thatsaid second wheel does not contact or engage the leading edge but doescontact the trailing edge during grinding of said workpiece whereby thetransverse edges are maintained sharp.

Preferably the actuating means includes a cam drive arrangement forcontrolling movement of said wheels into and out of contact with saidworkpiece.

In a preferred embodiment there are a plurality of pairs of abrasivewheels, each pair being driven in identical manner and each pair beingadapted to abrade a predetermined proportion only of the surface of theworkpiece. Thus the pairs of wheels may be axially spaced along the lineof said relative linear movement, the pairs of abrasive wheels beingdisplaced angularly with respect to one another.

The machine may be provided with an endless belt on which the workpiecesmay be supported for linear movement past the pair(s) of wheels.

Preferably the arrangement is such that the pairs of grinding wheels canbe adjusted to different positions around the circumference of theworkpiece, and then fixed in the desired position, to the effect that ina single operation, each pair of wheels abrades a separate longitudinalstrip on the workpiece, which can have any desired transverse orlongitudinal cross-section.

In order to reduce as far as possible the masses which have to be movedby the operation of the cams, each abrasive wheel is, according to theinvention, slidably mounted on a supporting arm independently of thesupport carrying the driving motor, in such fashion that the wheel canmove relatively to the surface of the workpiece. The abrasive wheel isconnected to the motor in such fashion that it can move relatively tothe motor and to the structure supporting the motor. Thus, for example,the abrasive wheel can be driven by a flexible shaft. This arrangementhas the further advantage that the wear of the wheel is considerablyreduced.

The invention is illustrated, merely by way of example, in theaccompanying drawing, in which:

FIGURE 1 is a side-elevational view which shows diagrammatically themain characteristics of a machine according to the present invention,

FIGURE 2 is an end elevation of part of the machine of FIGURE 1,

FIGURE 3 is a side elevation of part of the device shown in FIGURE 2,

FIGURE 4 is a part sectional end elevation through part of the machineof FIGURE 1,

FIGURE 5 shows a machining arrangement suitable for preparing the camsused in the machine according to the present invention,

FIGURE 6 represents a system using two machines according to the presentinvention, and

FIGURE 7 represents the process of grinding employed in the machineaccording to the present invention.

Referring to the drawing, there is shown a machine comprising a numberof abrading devices 1 to 5. Each device comprises two independentlycontrollable grinding wheels 6 and 7, 8 and 9, 10 and 11, 12 and 13, 14and 15, each consisting of a hub and a number of leaves of abrasivepaper projecting radially and supported by bundles of bristles. Thewheels may, alternatively consist of a foam-rubber wheel on which ismounted a strip of abrasive paper.

The abrading devices 1 to 5 are identical. Device 1 is shown in moredetail in FIGURES 2 and 3. Device 1 comprises wheels 6 and 7 rotatablymounted on arms 22 (only wheel 6 and its corresponding arm 22 is shownin FIGURES 2 and 3). Arms 22 are slidably mounted on frame members 24(only one shown) by guides 24a of which there are two for each arm 22.

Devices 22a are provided for biasing the arms 22 downwardly. Theseoperate under pneumatic pressure or are constituted by compressionsprings and serve to push the arms 22 with their abrasive wheelsconstantly against the workpieces. On each frame 24 there is fixedlymounted a drive motor 25, which drives the respective grinding wheelthrough a flexible shaft 23, which is under tension. The drive for thewheels are so arranged that the abrasive wheel 6 is driven counterclockwise (as seen in FIGS. 1 and 7), while the grinding wheel 7 isdriven clockwise.

The frames 24 for wheels 6 and 7 are mounted adjustably on a supportingarm 21. The supporting arm 21 is rather more than semi-circular (FIG. 2)and is aligned and vgenerally coaxial with a conveyor 17 for theworkpieces to be described hereinafter. On each side of the supportingarm 21 there is a dove-tail guide 21a so arranged that the frames 24 canbe adjusted to any position around the supporting arm 21, and can thenbe fixed in place by means of clamps of known kind, or eccentric levers,which are mounted pivotably in the frames 24 and clamp tight against thesurface of the supporting arm 21. Thus arm 21 supports two frames 24-,one on each side.

FIGURE 2 shows how the grinding devices 1 to 5 are in different angularpositions, i.e. angularly offset relative to the circumference of aworkpiece 16, so that each pair of abrasive wheels 6 and 7, 8 and 9, 10and 11, 12 and 13 and 14 and 15 abrades its own longitudinal strip onthe workpiece 16. Thus the device 1 is vertical, device 2 is inclined tothe vertical at an angle of 15, device 3 is at an angle of 45, thedevice 4 is at an angle of 90 and the device '5 is at an angle of 65 nthe other side of the vertical, each abrading assembly being offsetrelative to the others around the circular supporting arms 21 which arespaced axially along the line of movement taken by workpieces 16.

As shown, the grinding devices 1 to grind substantially one half of thecircumferential surface of the workpiece. However, the number ofgrinding devices can, of course, be as great as desired, whereby theycan grind most of the circumferential surface of the workpiece or eventhe entire surface.

Each of the two wheels of each abrading device for example, of thegrinding device 1, is controlled as to its position by a cam controlincluding a cam 26, the cam control acting against the biasof thecompression spring (or pneumatic device) 22a. Thus each of the arms 22,which supports the grinding wheels 6 to is connected through a Bowdendrive 27 (FIGS. 1 and 4) to one end of a pivoted cam follower lever 28.The sheath 29 of the Bowden cable is connected at one end to a reactionbush 30, which is mounted on the 'motor 25, and at the other end to acommon supporting strap 31. The pivoted cam follower levers 28 are allmounted on a common pivot axis 32. At one end of each lever is mounted acam follower roller 33, which follows the edge of the respective cam 26under the influence of the spring 22a. Thus each arm 22 has its own cam26 (FIG. 1), whose shape corresponds to the surface contour of therelevant strip of the workpiece being ground by the wheel attached tothe respective arm. In this way the workpiece 16 is ground by thegrinding wheels in predetermined strips, the shapes of which areprecisely determined by the movement of the grinding wheels relative tothe work-piece.

The cams 26 are all mounted on a common cylinder 34 (FIGURE 4) and arelocked in place, in the correct rotational relationship to each other,by two flanges 35, 36. Together, the cams are mounted as a completeassembly on a shaft 37 in such a way that it cannot rotate relative tothe shaft and is also secured against axial movement. The complete setof cams, constituting a program controller, can be exchanged for adifferent one, as required.

On the shaft 37 there are mounted two chain-drive sprocket wheels 38,one of which is driven by a chain 39 from a sprocket wheel 40 of agear-drive. The other sprocket wheel drives through a second chain 43 aspurwheel 41 of one drum -42 of the conveyor 17. The wheel 40 is driventhrough a chain-drive system 44, 45, 46 by a drive motor 47. In this waythe spur-wheel 40 drives the cam shaft 37 and the conveyor drum 42 atconstantly related speeds.

The conveyor 17 passes over drum 42 at one end and over a further drum48 at the other end. The workpieces 16 are firmly mounted on theconveyor 17. Each workpiece rests on a support which is adjustable inheight and is situated between two clamps 18, 19, one of which is fixedwhile the other is spring-biased. After the workpiece has been placed incontact with the adjustable support 20, the clamps 18 and 19 grip theworkpiece at its ends. Each workpiece is positioned with itslongitudinal axis in the direction of movement of the conveyor. All theworkpieces are at the same height. Each workpiece remains firmly clampedto the conveyor all through the grinding operation, and does not changeits position relative to the conveyor.

From FIGURE 2 it will be seen that the grinding devices are angularlydisplaced relatively to each other in planes at right angles to thedirection of movement of the workpieces. Thus between them the grindingwheels process the surface of the workpiece through an angle of 1 Eachpair of grinding wheels, for example, the pair of wheels 6, 7, processesa single longitudinal strip of the sursired longitudinal contour, isillustrated in FIGURE7F As a workpiece 16 proceeds from right to left asseen in FIGURE 7, the wheels 6 and 7 revolve as shown in oppositesenses. Wheel 6 is effective along the broken line 6a, and the grindingwheel 7 grinds along the broken line 7a. The grinding wheel 6 grinds theend 16a of the workpiece but lifts away from the surface before reachingthe other end 16b. On the other hand the grinding wheel 7 approaches theend 16a but does not touch it, but .does grind the other end 16b. Thuseach grinding wheel grinds one end only of the workpiece. Relative tothe movement of workpiece 16, the operative surface of wheel 6 (i.e. thelower portion thereof which contacts the workpiece) moves against thedisplacement of the workpieces whereas the operative surface of wheel 7moves with it. Wheel 6 grinds the trailing edge of the workpiece andwheel 7 grinds the leading edge thereof whereby the grinding wheels formsharp edges at each end of the workpiece.

The movement of the wheels 6 and 7 is controlled by their respectiveearns 26, the relative positions of these being determined before theyare clamped in placeon the shaft 37.

The cams 26 all have characteristic shapes, these being determined bythe predetermined profile which it is desired to impart to theworkpieces 16. One process for making these cams is shown in FIGURE 5.The arrangement comprises a conveyor belt 54 guided over two rollers 52,53. A model 51 is secured to the conveyor belt by means of two clamppieces 55 and 56, which hold it at its ends. A blank 26 for the cam ismounted tight on a shaft 57 of roller 52, in such fashion that the speedof rotation of the blank 26' is the same as that of the drum 52. Thesurface of the model 51 is followed by a copying roller 60 which ismounted on a slider 59 and pushed against this surface of the model by aspring 58. The position of the model in the clamps 55 and 56 is suchthat the copying roller 60 travels along that part of the surface forwhich the cam 26 is intended. The slider 59 can slide up and down inguides 61, and the model 51 can be adjusted by rotating about itslongitudinal axis so as to bring the copying roller 60 to the desiredstrip on the surface of the model. The other end of the slider 59 isattached to a cable 62 of a Bowden drive whose flexible sheath 63 isattached at one end to the guide frame of the slider, and at its otherend to a reaction bush 64. The other end of the cable 62 is attached toa shorter arm of a double arm lever 65, which is mounted on a shaft 66of a drive motor 67, but so that it can pivot freely on the shaft. Atthe end of the longer arm of this lever 65 is mounted a milling wheel66, which is driven by the motor 67 through a power train 68, 69, 70.This lever 65 pushes the milling wheel 66 against the circumference ofthe blank 26' according to the control provided by the copying roller 60acting on the model 51. The movement of the copying roller 60 along thesurface of the model 51 at the same 1 speed causes the longitudinalprofile of the particular.

longitudinal strip of the surface of the model to be transferredprecisely to the circumferential edge of the.

with spacer pads to lift the copying roller from the front edge or rearedge of the model, as required. On the other hand, there can be used forthis purpose two different models, one for making the cam for the firstgrinding wheel and therefore having a raised portion at the rear, andthe second model for the second grinding wheel and therefore having araised portion at the front.

When the workpieces have completed their journey along the grinding lineas seen in FIGURE 1, they are removed from the conveyor 17 and pass downa steep sliding surface 49 to a second simple conveyor belt 50, whicheither takes them away for further processing or, for example, canconvey it to a further grinding line. FIGURE 6 shows how two grindinglines A and B can be arranged next to each other and operated from asingle control station C. The raw blanks are taken from a storage hopperD and attached to the conveyor for the first grinding line A. Afterpassing along the grinding line A the workpieces are returned to thefront of the system by the conveyor belt 50 and then fed to the secondgrinding line B by the operator. Passing along the grinding line B theworkpieces are given a second surfacestrip treatment, and then pass outof the system.

It will be appreciated that many variations and alterations may beeffected to the described embodiments without departing from the scopeof the present invention, as defined by the appended claims. Thus Bowdencables need not be used for connecting the cams 26 to the abrasivewheels, hydraulic or electrical drives may be used. The arms 21 need notbe arcuate but could be of any other shape provided the grinding devices1 to 5 can be disposed at angularly spaced locations about the conveyor17. The motors 25 could be mounted on the arms 22 with the grindingwheels 6 to and thus a solid drive could be provided therebetween inplace of the flexible drive 23. However, the mobile mass will becorrespondingly higher and this is not welcome. The workpieces need notbe mounted on an endless conveyor, nor need they be clamped in themanner described above, provided they can be moved past the series ofgrinding wheels and held rigid relative thereto.

We claim:

1. A machine for abrading the surface of an elongated workpiece havingsharp edges disposed transversely of its longitudinal dimension, saidmachine comprising first and second abrasive wheels, means for effectingrelative linear movement between the wheels and said workpiece along thelength thereof, means for rotating the wheels in a common planecontaining a line of said linear movement and in opposite senses wherebythe movements of the operative surfaces of said first and secondabrasive wheels are respectively with and against the movement of saidworkpiece relative to said wheels, and a cam-drive arrangementcontrolling movement of said wheels into and out of contact with saidworkpiece, said cam-drive arrangement ensuring that the first wheelcontacts the leading transverse edge of the workpiece but does notcontact the trailing edge thereof and for ensuring that said secondwheel does not contact said leading edge but does contact said trailingedge during abrading of said workpiece whereby the transverse edges aremaintained sharp.

2. A machine for abrading the surface of an elongated workpiece which iscontoured in its longitudinal direction and which has sharp edgesdisposed transversely of its longitudinal dimension, said machinecomprising first and second abrasive wheels, means for effectingrelative linear movement between the wheels and said workpiece along thelength thereof, means for rotating the wheels in a common planecontaining a line of said linear movement and in opposite senses wherebythe movements of the operative surfaces of said first and secondabrasive wheels are respectively with and against the movement of saidworkpiece relative to said wheels, and a cam-drive arrangementcontrolling movement of said wheels into and out of contact with saidworkpiece, said cam-drive arrangement controlling movements of saidwheels corresponding to the contour required on said workpiece andensuring that the first wheel contacts the leading trans verse edge ofthe workpiece but does not contact the 6 trailing edge thereof and forensuring that said second wheel does not contact said leading edge butdoes contact said trailing edge during abrading of said workpiecewhereby the transverse edges are maintained sharp.

3. A machine for abrading the surface of an elongated workpiece havingsharp edges disposed transversely of its longitudinal dimension, saidmachine comprising first and second abrasive wheels, means for effectingrelative linear movement between the wheels and workpiece along thelength thereof, a frame member, a pair of arms slidably mounted on saidframe member for movement at right angles to said linear movement, meansrotatably mounting said first and second abrasive wheels on therespective arms, means for rotating the wheels in a common planecontaining a line of said linear movement and in opposite senses wherebythe movements of the operative surfaces of said first and secondabrasive wheels are respectively with and against the movement of saidworkpiece relative to said wheels, and actuating means for ensuring thatthe first wheel contacts the leading transverse edge of the workpiecebut does not contact the trailing edge thereof and for ensuring thatsaid second wheel does not contact said leading edge but does contactsaid trailing edge during abrading of said workpiece whereby thetransverse edges are maintained sharp.

4. A machine for abrading the surface of an elongated workpiece havingsharp edges disposed transversely of its longitudinal dimension, saidmachine comprising first and second abrasive wheels biased towards saidworkpiece, means for effecting relative linear movement between thewheels and workpiece along the length thereof, means for rotating thewheels in a common plane containing a line of said linear movement andin opposite senses whereby the movements of the operative surfaces ofsaid first and second abrasive wheels are respectively with and againstthe movement of said workpiece relative to said wheels, and a cam-drivearrangement for controlling movement of said wheels into and out ofcontact with said workpiece and including a control connection 'betweeneach said wheel and a respective control cam acting against the bias ofsaid wheels in controlling the positions of said wheels, and ensuringthat the first wheel contacts the leading transverse edge of theworkpiece but does not contact the trailing edge thereof and forensuring that said second wheel does not contact said leading edge butdoes contact said trailing edge during abrading of said workpiecewhereby the transverse edges are maintained sharp.

5. A machine for abrading the surface of an elongated workpiece havingsharp edges disposed transversely of its longitudinal dimension, saidmachine comprising first and second abrasive wheels biased towards saidworkpiece, means for effecting relative linear movement between thewheels and said workpiece along the length thereof, means for rotatingthe wheels in a common plane containing a line of said linear movementand in opposite senses whereby the movements of the operative surfacesof said first and second abrasive wheels are respectively with andagainst the movement of said workpiece relative to said wheels, and acam-drive arrangement for controlling movement of said wheels into andout of contact with said workpiece, said cam-drive arrangement includinga Bowden-cable drive for each wheel continuously tensioned by the biasof said wheels toward said workpiece, and respective cams controllingeach Bowden-cable drive and so constructed and arranged that the firstwheel contacts the leading transverse edge of the workpiece but does notcontact the trailing edge thereof, and that said second wheel does notcontact said leading edge but does contact said trailing edge duringabrading of said workpiece whereby the transverse edges are maintainedsharp.

6. A machine for abrading the surface of an elongated workpiece havingsharp edges disposed transversely of its longitudinal dimension, saidmachine comprising first and second abrasive wheels biased towards saidworkpiece, means for elfecting relative linear movement hetween thewheels and workpiece along the length thereof, a frame member, arespective arm assigned to each of said wheels and slidably mounted onsaid frame member for movement at right angles to said relative linearmovement, means rotatably mounting said first and second abrasive wheelson said arms, means for rotating the wheels in a common plane containinga line of said linear movement and in opposite senses whereby themovements of the operative surfaces of said first and second abrasivewheels are respectively with and against the movement of said workpiecerelative to said wheels, and a cam-drive arrangement for controllingmovement of said wheels into and out of contact with said workpiece,said cam-drive arrangement comprising a respec tive cam assigned to eachwheel, a respective pivoted lever forming at one end a cam followerriding against the respective cam, and a respective Bowden-cable drivehaving a sheath and a flexible cable continuously tensioned by the biasof the respective wheel toward said workpiece, one end of said cablebeing attached to the respective arm, the corresponding end of thesheath for the cable being fixed relative to said frame member, theother end of the respective cable being fixed to the other end of therespective pivoted lever, said cams, cables and levers being soconstructed and arranged that the first wheel contacts the leadingtransverse edge of the workpiece but does not contact the trailing edgethereof, and that said second wheel does not contact said leading edgebut does contact said trailing edge during abrading of said workpiecewhereby the transverse edges are maintained sharp.

7. A machine as defined in claim 6, further comprising a respectiveroller mounted on said one end of each pivoted lever and resting on theperiphery of said cam, the roller being urged into contact with the camby the bias of the respective wheel.

8. A machine for abrading the surface of an elongated workpiece havingsharp edges disposed transversely of its longitudinal direction, saidmachine comprising first and second abrasive wheels, means for effectingrelative linear movement between the wheels and workpiece along thelength thereof, a respective frame member assigned to each wheel, an armslidably mounted on each frame member for movement at right angles tosaid relative linear movement, means mounting a respective one of saidwheels on each of said arms, a respective compression spring disposedbetween each arm and the respective frame member to bias the respectivewheel against said workpiece, means for rotating the wheels in a commonplane containing a line of said linear movement and in opposite senseswhereby the movements of the operative surfaces of said first and secondabrasive wheels are respectively with and against the movement of saidwork piece relative to said wheels, and actuating means for ensuringthat the first wheel contacts the leading transverse edge of theworkpiece but does not contact the trailing edge thereof and forensuring that said second wheel does not contact said leading edge butdoes contact said trailing edge during abrading of said workpiecewhereby the transverse edges are maintained sharp.

9. A machine for abrading the surface of an elongated workpiece havingsharp edges disposed transversely of its longitudinal direction, saidmachine comprising first and second abrasive wheels, means of effectingrelative linear movement between the wheels and workpiece along thelength thereof, a frame member assigned to each wheel, arms slidablymounted on said frame member for movement at right angles to saidrelative linear movement, means mounting each of said wheels on arespective one of said arms, a motor for each wheel mounted on saidframe member, a flexible drive extending from the motor to therespective wheel, the motors rotating the wheels in a common planecontaining a line of said linear movement and in opposite senses wherebythe movements of the operative surfaces of said first and secondabrasive wheels are respectively with and against the movement of saidworkpiece relative to said wheels, and actuating means for ensuring thatthe first wheel contacts the leading transverse edge of the workpiecebut does not contact the trailing edge thereof and for ensuring thatsaid second wheel does not contact said leading edge but does contactsaid trailing edge during abrading of said workpiece whereby thetransverse edges are maintained sharp.

10. A machine for abrading the surface of an elongate workpiece havingsharp edges disposed transversely of its longitudinal direction, saidmachine comprising a plurality of pairs of abrasive wheels, each paircomprising first and second abrasive wheels adapted to abrade apredetermined portion only of the surface of the work-t piece, means foreffecting relative linear movement between the wheels and workpiecealong the length thereof,

means for rotating the wheels of each pair in a common plane containinga line of said linear movement and in opposite senses whereby themovements of the operative surfaces of each pair of first and secondabrasive wheels are respectively with and against the movement of saidworkpiece relative to said wheels, and actuating means for ensuring thatthe first wheel of each pair contacts the leading transverse edge of theworkpiece but does not contact the trailing edge thereof and forensuring that said second wheel of each pair does not contact saidleading edge but does contact said trailing edge during abrading of saidworkpiece whereby the transverse edges are maintained sharp.

11. A machine for abrading the surface of an elongated workpiece havingsharp edges disposed transversely of its longitudinal direction, saidmachine comprising a plurality of pairs of abrasive wheels, each paircomprising first and second grinding wheels, means for effectingrelative linear movement between the wheels and workpiece along thelength thereof, said pairs of abrasive wheels being axially spaced apartin said direction and being disposed angularly with respect to oneanother whereby each pair of wheels is adapted to abrade a predeterminedlimited portion only of the surface of said workpiece, means forrotating the wheels of each pair in a common plane containing a line ofsaid linear movement and in opposite senses whereby the movements of theoperative surfaces of each pair of said first and second abrasive wheelsare respectively with and against the movement of said workpiecerelative to said wheels, and actuating means for ensuring that the firstwheel of each pair contacts the leading transverse edge of the workpiecebut does not contact the trailing edge thereof and for ensuring thatsaid second wheel of each pair does not contact said leading edge butdoes contact said trailing edge during abrading of said workpiecewhereby the transverse edges are maintained sharp.

12. A machine for abrading the surface of an elongated workpiece havingsharp edges, disposed transversely of its longitudinal direction, saidmachine comprising a plurality of pairs of abrasive wheels, each paircomprising first and second abrasive wheels, means for effectingrelative linear movement between the wheels and workpiece along thelength thereof, a respective frame member for the wheels of each pair, arespective arm assigned to each wheel of a respective pair slidablymounted on each said frame member for movement at right angles to saidrelative linear movement, means rotatably mounting a respective wheel oneach arm, a plurality of arcuate supports axially spaced apart along theline of said relative linear movement, said frame members being clampedto said arcuate supports such that the frame members are offsetangularly with respect to one another and each pair of wheels can abradea predetermined portion only of the surface of said workpiece, means forrotating the wheels of each pair in a common plane containing a linesecond abrasive wheels of each pair are respectively with and againstthe movement of said workpiece relative to said wheels, and actuatingmeans for ensuring that the first wheel of each pair contacts theleading transverse edge of the workpiece but does not contact thetrailing edge thereof and for ensuring that said second wheel of eachpair does not contact said leading edge but does contact said trailingedge during abrading of said workpiece whereby the transverse edges aremaintained sharp.

13. A machine as defined in claim 12 wherein sliding dovetailconnections are provided on each said arcuate support to support saidframe members.

14. A machine for abrading the surface of an elongated workpiece havingsharp edges disposed transversely of its longitudinal direction, saidmachine comprising a plurality of pairs of abrasive wheels, each paircomprising first and second abrasive wheels, means for effectingrelative linear movement between the wheels and workpiece along thelength thereof, means for rotating the wheels of each pair in a commonplane containing a line of said linear movement and in opposite senseswhereby the movements of the operative surfaces of said first and secondabrasive wheels are respectively with and against the movement of saidworkpiece relative to said wheels, and a cam-drive arrangement forcontrolling movement of said wheels into and out of contact with saidworkpiece, said arrangement comprising a separate cam for each wheel, acommon shaft supporting all of said cams and a drive for said shaft torotate said cam in common, said cam-drive arrangement being soconstructed and arranged that the first wheel of each pair contacts theleading transverse edge of the workpiece but does not contact thetrailing edge thereof and that said second wheel of each pair does notcontact said leading edge but does contact said trailing edge duringabrading of said workpiece whereby the transverse edges are maintainedsharp.

References Cited UNITED STATES PATENTS 1,006,881 10/1911 Russell 51-401,042,817 10/1912 Newman 5140 X 2,107,184 2/1938 Lasker 74501 2,948,0868/ 1960 Eger 51-80 3,274,736 9/1966 Brokaw 51-127 X 3,295,261 1/1967Murray 5176 X DONALD R. SCHRAN, Primary Examiner. D. G. KELLY, AssistantExaminer.

